Creating a user account means that you supply a username (your real name or a nickname) and a password. The system will reject a username that is already in use. A user account is created only once. You are then "logged in". Next time you log in you supply your username again and demonstrate with the password that you are the same person.

Edits you make are recorded under your username. If you are not logged in your edits are recorded under your IP address.

Some projects using MediaWiki software form a family in the sense that one logs in to the family as a whole, and that common preference settings apply. Notably this is the case for the more than 1000 Wikia projects. On Wikimedia projects setting preferences (except for email, username and password) are currently done separately on each wiki. You may like to maintain a cross-wiki identity by using the same username on each wiki that you use, if that name is still free.

You don't have to log in to read any MediaWiki wiki. You don't even have to log in to edit a MediaWiki wiki - anyone can edit almost any page, even without logging in.

However, it's still a good idea to log in, for these reasons:

Other users will be able to recognise you by your username when you make changes to pages. As a "name" an IP address is somewhat clumsy. Also, if you use computers at different locations (home, office, internet cafe, etc.) you have a different IP-address in each case; even in the same location, depending on the Internet connection, the IP-address may be different each time. Therefore a username is better to maintain an identity.

You will have your own user page where you can write a bit about yourself, and a user talk page which you can use to communicate with other users.

You will be able to mark an edit as minor, which avoids inconvenience for other users.

You will be able to keep track of changes to modules you are interested in using a watch list.

If you choose to give an email address, other users will be able to contact you by email. This feature is anonymous - the user who emails you will not know your email address. You don't have to give your email address if you don't want to.

Check the privacy policy of the individual site you're visiting, if any (for example, Wikimedia's privacy policy)

First, make sure that your browser accepts cookies. Some browsers can accept or reject cookies from individual sites; users of these should configure the browser to accept cookies from each wiki you plan to edit, such as wikipedia.org.

Click on the Log in link at the top right of the page. You will then be prompted to enter your username and password. If you haven't logged in before, you will need to use the link provided to create an account. You may give your email address if you like.

If you click the box Remember me, you will not have to give your password again when you access MediaWiki wiki from the same computer. This feature will only work if your password was not generated by the Mediawiki software.

If you appear to be able to log in, but as soon as you try to look at a page after the 'Log in successful' page you appear logged out again, it is very likely to be a cookie problem. If you are certain that cookies are enabled, make sure that you haven't inadvertently listed //meta.wikimedia.org on a list of sites to never allow cookies for (This feature is available in (at least) Mozilla Firebird (Firefox) 0.6 and above and Microsoft Internet Explorer version 6 and above). Also make sure your computer's date and time are set correctly; if they are not, cookies may expire before they are supposed to. Note that some firewall and ad-blocking software may interfere with the cookie that Meta uses to keep a person logged in.

In addition to these steps, check to make sure PHP's directory for storing session data is writable. This directory can be found in the php.ini file under the session.save_path setting. Errors in this php.ini setting can also cause other problems. Examples of these errors are referencing a non-existent directory or leaving out " marks around the directory name. Random Wiki pages or edit previews might appear blank in Internet Explorer, but not with other browsers. Also, the Save Page button might act as if one had pressed the Show Preview button when a user is logged in, but work correctly when one is not logged in.

A user may occasionally find him/herself "automatically" logged out in between beginning an edit and saving it, or when switching between multiple Meta pages open in multiple windows. This can be a result of your browser's cookie, cache, or firewall settings, but due to the nature of the MediaWiki software; some user ID information is stored in the servers and sometimes, especially during heavy server load, the system can "glitch" and your ID information will be misplaced, resulting in a logout. Regardless of the reason for the logout, the simplest solution to the problem is to check the Remember me box. If you do this on a computer that can be accessed by more than one person (i.e. at the library, at work, at school), please find and erase your user ID cookies after your editing session.

If you log in and enabled the cookie feature, a subsequent log in as a different user without the cookie feature enabled will appear as logged out.

Make sure the Internet Guest Account (eg. IUSR_FOOBAR, nobody, or apache) has write permissions to the folder listed in the "session.save_path" variable of the php.ini file.

If you enter an e-mail address when signing up for the account, or in your Preferences, you can request on the login screen for a temporary password to be sent to that address, which will allow you to retrieve your account. If you did not enter an e-mail address, or the address was out of date, you will have to create a new account.

To create an account, select Log in (top right of page) then create an account. You usually need only provide a username and password. Some wikis require a visual captcha (Completely Automated Public Turing test to tell Computers and Humans Apart). Users with text, speech, or legacy browsers will be unable to create an account if they can not view this image. If you are unable to view captchas, contact an administrator.

As a logged in user, you will be able to create your own user page and user talk page. When you are logged in, you will see your username displayed at the top right of the page. Click on this to get to your user page, which you can edit in the same way as any MediaWiki wiki page.

Most users write a little bit about themselves and their interests on their user page.

You also have a User talk page. You can access this by clicking on the Talk link next to your username at the top right of the page. Other people may write messages in your user talk page by editing it, and you can respond. See Help:Talk page for more.

Note that in some sans-serif fonts I (capital-i) and l (lowercase-L) look exactly the same, e.g. in Arial: I and l. If your username contains one of the two, it may be wise to register another account, but swap the letters (so if your username contains lowercase-L change that to capital-i). This is to prevent impersonation. You may then redirect the userpage of the "dummy" account to your real account.